Custom integrated circuits for various applications employ a binary counter to implement a timing function. For example, custom integrated circuits are presently available for detecting unauthorized entry of an automobile. The circuit utilizes a binary counter as a timer for controlling the time of activation of an alarm device following detection of unauthorized entry. Because of cost considerations, the frequency of the time base is relatively high and is divided down on the chip to provide, for example a 1 Hz. input to the counter. With a 1 Hz. input, an 8-bit binary counter provides an approximate 4 minute time interval for activation of the alarm device following intrusion. The timer interval is relatively large in relation to the time required to test the remainder of the circuit and, accordingly, it is desirable to reduce the time interval necessary to test the operability of the counter.